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Anomalous Stark shifts in single vertically coupled pairs of InGaAs quantum dots |
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| Authors: | R Oulton AI Tartakovskii A Ebbens JJ Finley DJ Mowbray MS Skolnick M Hopkinson |
| Institution: | aDepartment of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK;bExperimentelle Physik II, Universität Dortmund, D-44221 Dortmund, Germany;cWalter Schottky Institut, Technische Universiät München, D-85748 Garching, Germany;dDepartment of Electrical and Electronic Engineering, University of Sheffield, Sheffield S3 7RH, UK |
| Abstract: | Vertically coupled Stranski Krastanow quantum dots (QDs) are predicted to exhibit strong tunnelling interactions that lead to the formation of hybridised states. We report the results of investigations into single pairs of coupled QDs in the presence of an electric field that is able to bring individual carrier levels into resonance and to investigate the Stark shift properties of the excitons present. Pronounced changes in the Stark shift behaviour of exciton features are identified and attributed to the significant redistribution of the carrier wavefunctions as resonance between two QDs is achieved. At low electric fields coherent tunnelling between the two QD ground states is identified from the change in sign of the permanent dipole moment and dramatic increase of the electron polarisability, and at higher electric fields a distortion of the Stark shift is attributed to a coherent tunnelling effect between the ground state of the upper QD and the excited state of the lower QD. |
| Keywords: | Quantum dot molecules Coherent coupling |
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